Re: Documentation example doesn't compile with gcc

[Martin Sebor]

Misha Aizatulin wrote:

hi all,

  at the very end of http://stdcxx.apache.org/doc/stdlibug/34-2.html
there is an example of using a reference to create a "copy" of cout.
However this example doesn't initialize the defined reference at once
(which is required in C++) and for this reason doesn't compile with my
gcc 4.2.1.

That's definitely incorrect. The uninitialized reference is not
C++ and as noted in LWG issue 50, stream objects are not copyable.
The next C++ Standard makes that explicit by declaring the copy
ctor and copy assignment operator of class ios_base deleted.

I opened STDCXX-1024 to have the problematic example removed:
  http://issues.apache.org/jira/browse/STDCXX-1024

LWG issue #50 for reference
http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html#50

Thanks for pointing it out!
Martin

  For convenience here is the example:

int main(int argc, char *argv[])
{
  std::ostream& fr;
  if (argc > 1)
    fr = *(new std::ofstream(argv[1]));
  else
    fr = std::cout;

  fr << "Hello world!" << std::endl;

  if (&fr!=&std::cout)
    delete(&fr);
}

Cheers,
  Misha